SAN FRANCISCO — The nation’s largest state bar association is overhauling ethics rules for attorneys for the first time in 30 years, and some lawyers are unhappy about a proposal that would open them up to discipline for having sex with clients.

California currently bars attorneys from coercing a client into sex or demanding sex in exchange for legal representation.

Supporters of an all-out ban say the relationship between a lawyer and client is inherently unequal, so any sexual relationship is potentially coercive. But some attorneys say it’s an unjustified invasion of privacy.

The proposal is part of a long-awaited shake-up of the state bar association’s ethics rules for attorneys, which were last fully revised in 1987. Lawyers who violate the regulations are subject to discipline ranging from private censure to loss of their legal license.

A state bar commission has spent months crafting and amending 70 rules under goals set by the California Supreme Court. Other changes under consideration would allow the state bar to discipline attorneys for discrimination and harassment even without a separate finding of wrongdoing. The current rule requires a final determination of wrongful discrimination in a lawsuit or other proceeding before the state bar can take action.

Still another change would bring California in line with other states by subjecting prosecutors to discipline for failing to turn over evidence they know or reasonably should know would help the defense.

“The first and foremost goal is to promote confidence in the legal profession and administration of justice and ensure adequate protection to the public,” said Lee Smalley Edmon, a California appellate court judge and head of the commission revising the rules.

The sex ban has divided the rules revision commission, though similar restrictions are in place in other states. As of May 2015, 17 states had adopted a blanket sex ban drafted by the American Bar Association, according to an ABA committee that looked at implementation of the group’s ban.

Like the ABA ban, California’s proposal creates an exception when the sexual relationship preceded the attorney-client relationship.

At an October commission meeting, lawyer and commission member Daniel Eaton said the current rule regarding sex isn’t working, and pointed to a lack of disciplinary action against attorneys as evidence.

Between September 1992 and January 2010, the state bar investigated 205 complaints of misconduct under the current sex restriction, according to an analysis of state bar data that accompanied the proposal. It imposed discipline in only one case.

The current rule also forbids sex if it causes the lawyer to “perform legal services incompetently.”

A bright-line rule would provide clarity to attorneys and remove the difficulty of proving the sexual relationship was the result of coercion or negatively affected the lawyer’s performance, supporters say.

“If we have a very flat guideline, it gets out of the area of subjectivity,” said Andrew Servais, chair of the San Diego County Bar Association’s legal ethics committee.

Opponents of the ban, including the Los Angeles County Bar Association’s ethics committee, say it’s unnecessary and would be struck down as an unconstitutional violation of fundamental privacy rights.

No empirical or even reliable anecdotal evidence shows a ban is needed to protect the public or regulate the legal profession, James Ham, another lawyer on the commission, said in a dissent filed with the commission.

He added, “Proponents of a complete ban cannot articulate why a lawyer should be disciplined for sexual relations with a mature, intelligent, consenting adult, in the absence of any quid pro quo, coercion, intimidation or undue influence.”

The revisions commission modified the proposal at the October meeting to create an exception from the sex ban for lawyers’ spouses or registered domestic partners. It also required the state bar to consider whether a client would be “unduly burdened” by an investigation of sexual misconduct if someone other than the client filed the complaint.

The bar’s board of trustees approved an additional public comment period on the sex ban rule earlier this month. The rules commission has until the end of March 2017 to get the board’s approval for the proposals and send them to the California Supreme Court, which will have final say on the changes.